Telephone system



Patented Apr. 4, 1944 AUNITED Sintes rArENr Norrici:

TELEPHONE SYSTEM Leonard M. Blessing, Alexandria, Va., assigner to American Telephone and Telegraph Company, a corporation of New York reparation Api-i1 27, 1943, serial No. 484.681

a'olaims.

This invention relates to transmission systems, such for example as telepllone systems, and more particularly to improvements in the switchboard apparatus used in such systems.

It has been found thatv in certain localities exchanges, particularly the larger private branch exchanges; are subject to heavy in and out station movement. l In. other words, subscribers at such an. exchange mightbe. transferred frequently to other localities, and until their sets were assigned to others, incoming calls for these subscribers would be routed to an intercept operator so that the incoming callers couldv be informed that the particular called subscriber was no longer available at his previous station.. lnv order to transfer an incoming call to ani-ntercept operator it has been the practice forthe plant maintenance force to disconnect all of the cross connections between two terminal strips associated with a, particular line and to connect these cross connections to a terminal strip associated with the intercept operator. When the line is reassigned to another subscriber all of these cross connections `would have to be restored to their original condition. When the in and out station movement in the exchange is heavy, this procedure frequently adds up to a sizeable eliort.. It is the primary object of this invention to provide a simpler and easier arrangement for effecting the transfer of an incoming call to an intercept operator and its subsequent reassignment to a new subscriber than the arrangements heretofore used. It is one of the features of the invention that only one rather than all of the cross connections between two terminal strips `will have to be disconnected and then connected to the terminal stripV associated with the intercept operator. Other objects and features of the invention will appear more fully from the detailed description thereof hereinafter given.

The invention may be more fully understood from the following description together with the accompanying drawing in the Figures 1 and 2 of which the invention is illustrated. Fig. 1 illustrates arrangements utilized in the prior art. Eg. 2 illustrates the arrangements of the invention. Similar reference characters have been utilized to denote like parts in both iigures.

In l are shown arrangements which have been utilized in the past to transfer an incoming call from a subscribers line to an intercept cperator. A terminal strip I is shown having tip, ring sleeve conductors extending to the banks of a connector of a step-by-step machine switching arrangement. The terminal stripv i might also have tip, ring and sleeve conductors and an additionalV conductor S' extending to a manual operators position. A second terminal strip 2 is provided. Cross connections 3, 4f, 5 and 6 connect the contacts of terminal strip- I with correspending contacts on terminal strip 2. Extending from terminal strip 2 are tip and ring conductors terminating in the make contacts of a cut-oil relay l. A sleeve conductor extends from terminal strip 2 to the winding of the cut-off relay Another conductor S' extends from the terminal strip 2 to the contact and lower armature of the cut-off relay l. When a call comes in for the subscribers set i0, ground will be applied to either of the sleeve conductors shown associated with terminal strip I, and thence will be applied over cross connection 5 and the sleeve conductor associated with terminal stripv 2, through the winding of cut-'oir relay 'I, to battery and ground. This will operate the: cut-ofirelay and connect the subscribersl set Il) by means of conductors 8 and 9l to the tip and. ring conductors connected to terminal strip 2, and thence over cross connections 3 and 4 to the tip and ring conductors connected to terminal strip I. The lower armature of the cut-oil relay I will apply ground to conductor S and thence over cross connection il to conductor S connected to terminal stripv I for the purpose of giving a busy signal. If the subscriber havingl subscribers set I0 should move away from the vicinity of the private branch exchange, it would be desirable to have incoming calls over this subscribers set transferred to an intercept operator until the subscribers set it is assigned to another subscriber. To accomplish this it has been the practice for the maintenance force to open all of the cross connections 3i, fl, 5 and S between terminal strips I and 2 at points such as indicated at I5. Conductors I2, I3 and I4 which lead to the tip, ring and sleeve contacts of a terminal strip I I associated with an intercept operator would then be connected across cross connections 3, 4 and 5 as shown. Accordingly incoming calls would thus be transferred directly to the intercept operator. Obviously when the subscribers set il) was assigned to another subscriber, the cross connections 3, 4, 5 and 6 would all have to be closed again and the conductors I2, I3 and I4 removed therefrom. As heretofore pointed out, when the in and out station movement is heavy, as is apt to be the case in a large private branch exchange, this would entail considerable work for the maintenance force.

In Fig. 2 are shown the arrangements of the invention. An .incoming call for the subscriber causes ground to be applied to either of the sleeve conductors associated with the terminal strip I and causes the cut-off relay 'I to operate and connect conductors 8 and 9 to the tip and ring conductors and cross connections 3 and 4 so that the call will go direct to the subscribers set I 0. To transfer an incoming call to the intercept operator, conductors I6 and II are provided and are connected to the tip and ring conductors extending from terminal strip 2 by means of additional contacts on the cut-off relay 'I. The conductors I6 and I'I will be connected to these tip and ring conductors when the cut-01T relay 'I is unoperated, but will be disconnected therefrom when the cut-off relay I is operated. Conductors ISand II terminate in the tip and ring contacts of a terminal strip II,

point such as I5 and connect the cross connection 5 as indicated by the dotted line 2U to contact I9 of terminal strip I. All of the other cross connections will not have to be disturbed. As cross connection 5 has been opened as at I5,

ground applied to the sleeve conductors con- 51 nected to terminal strip I will not operate the cut-off relay 'I. Accordingly an incoming call will be transmitted over the tip and ring conductors associated with terminal strip I, over cross connections 3 and 4, over the tip and ring conductors connected to terminal strips I and 2, and thence over conductors 'I5 and I'I to the tip and ring contacts of terminal strip II connected to the intercept operator. Ground connected to either of the sleeve circuits connected to terminal strip I will be applied from cross connection 5 to conductor I8, and thence to the sleeve contact of terminal strip II. It will be seen that the arrangements of the invention provide that only one of the cross connections, namely cross connection 5, will have to be opened and only one connection from the cross connections, such as cross connection 5 to contact I9, will be necessary. Accordingly the arrangements of the invention provide a simpler and easier method for transferring an incoming call to an intercept operator than the arrangements heretofore referred to, and will save considerable time on the part of the maintenance force. It is obvious that the switchboard would have other terminal strips corresponding to terminal strips I and 2, and other subscribers lines with their individual This contact is connected by conductor` cut-oil relays. Accordingly additional conductors, such as 22, might be bridged across conductors I6 and I'l. Each pair of additional conductors, such as 22, would terminate at additional contacts provided on other of the cut-oil relays, and additional conductors, such as 23, Would be provided on the terminal strip VII to lead to other terminal strips, such as I. In this Way the arrangements of the invention would provide means for transferring av plurality of incoming calls to an intercept operator.

While the invention has been disclosed as embodied in certain specic forms which are deemed desirable, it is understood that it is capable oi embodiment in many and other widely varied forms without departing from the spirit of the invention as dened by the appended claims.

What is claimed is:

1. In a telephone switchboard a rst terminal strip, tip, ring and sleeve conductors terminating at said terminal strip, a second terminal strip, tip, ring and sleeve cross connections between said rst and second terminal strips, av subscribers line, a cut-off relay for said line, tip and ring conductors connected to said second terminal strip and terminating at the make contacts of said cut-off relay, a third terminal strip, a pair of conductors connected across said last mentioned tip and ring conductors when said cut-off relay is unoperated, said pair of conductors being connected to the vtip and ring contacts of said third terminal strip, means for connecting said sleeve cross connection when opened to the sleeve contact of said third terminal strip, and tip, ring and sleeve conductors leading from said third terminal strip to an intercept operators position. Y

2. In a telephone switchboard a first set of terminal strips, tip, ring andsleeve conductors terminating at each of said terminal strips, a second set of terminal strips, tip, ring and sleeve connections between each of the terminal strips of said first and second sets, a plurality of subscribers lines, cut-ofi` relays for each of said lines, tip and ring conductors connected to each vof the terminal strips of said second set and terminating at the make contacts of said cut-off relays, a terminal strip connected to an intercept operators position, pairs of conductors connected across said last mentioned tip and ring conductors when said cut-olf relays are unoperated, said pairs of conductors being connected to the tip and ring contacts of said last mentioned terminal strip, and means for connecting said sleeve cross connections when opened to the sleeve contact of said last mentioned terminal strip.

LEONARD M. BLESSING. 

